Collapsible and/or assembled filter housing and filter used therewith

ABSTRACT

A filter assembly including a rectangular inlet frame having a rectangular inlet opening, a rectangular outlet frame, a housing body being collapsible to have a flattened shipping state and an erect state, the collapsible housing body in the erect state being rectangular and interposed between the rectangular inlet frame and the rectangular outlet frame in an assembled state, and at least one filter having filter media installed in the rectangular inlet opening in generally sealing relation thereto and projecting from the inlet frame toward the outlet frame in the assembled state.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This patent application claims the benefit of U.S. Provisional PatentApplication No. 61/491,136, filed May 27, 2011; and U.S. ProvisionalPatent No. 61/495,230, filed Jun. 9, 2011; and U.S. Provisional PatentApplication No.61/591,157, filed Jan. 26, 2012, which are now pending,the entire teachings and disclosure of which are incorporated herein byreference thereto.

FIELD OF THE INVENTION

This invention generally relates to air filtrations systems, and moreparticularly, to filtration systems used in animal confinementfacilities or in other filtration applications and/or to an alternativeto V-Bank Filters.

BACKGROUND OF THE INVENTION

One of the concerns in agricultural animal confinement facilities,particularly in the agricultural swine industry, is the control of thespread of disease. For example, disease agents such as mycoplasma, theswine influenza virus, and the porcine reproductive and respiratorysyndrome virus (PRRSV) have had a significant negative impact on swineproduction. It has been estimated that PRRSV alone may increase theaverage cost of swine production by $5.60 to $7.62 per head.

One method that has proven effective is reducing the spread of theaforementioned disease agents is filtration of the air in animalconfinement facilities. For example, high-efficiency air filters haveproven to be effective at reducing the rate of airborne transmission ofthese disease agents. One of the challenges for the swine productionindustry is how to best provide the needed high-efficiency airfiltration in a practical manner at the lowest cost, with ease of filterchange out, and with reliability for the environmental application.

Facilities, such as those used for animal confinement, may have dozens,if not more, separate filtration units installed throughout thefacility. Assembly, installation and maintenance of these filtrationunits is generally expensive and time-consuming. Various examples in theart are disclosed in Crabtree et al., US 2010/0313760 and Devine et al.,US 2009/0301402, the entire disclosures of which are hereby incorporatedby reference in their entireties. A test standard for sufficientlyfiltering out PRRSV is advanced in the '402 publication to Devine et al.as well as air flow requirements desired for animal confinementbuildings.

Heretofore, commercially employed virus filters for animal confinementbuildings (e.g. for removal of PRRSV) such as in the above examples haveemployed V-Bank Filters with a MERV 16 type media that is either wetlaid microglass and/or synthetic polymeric fibers. V-bank filters inthese applications have been used and are highly desirable due to thehigh flow rates experienced (e.g. typically a filter (2′ high×2′ wide)needs to handle at least 1000 CFM) as substantial air flow for hogconfinement to facilitate ventilation for proper humidity, temperatureand air quality (e.g. ammonia, and other airborne contaminants andbyproducts of hog confinement and manure pits). The substantial headerdepth (e.g. filter elements are typically about 12 inches deep in thedirection of air flow; also referred to as header depth) and open Vshaped cavities between different filter media packs of V-Bank filtersprovide the capability for handling the substantial flow volume andrequirements, while at the same time filtering the PRRS virus. Further,it is known to add a prefilter due to the external environment that isoften laden with dust. For example pre-filters are known in combinationwith V-banks such as Rivera et al. U.S. Pat. No. 6,447, 566, the entiredisclosure of which is hereby incorporated by reference.

BRIEF SUMMARY OF THE INVENTION

In one aspect, embodiments of the invention provide a filter assemblyincluding a rectangular inlet frame having a rectangular inlet opening,a rectangular outlet frame, a housing body being collapsible to have aflattened shipping state and an erect state, the collapsible housingbody in the erect state being rectangular and interposed between therectangular inlet frame and the rectangular outlet frame in an assembledstate, and at least one filter having filter media installed in therectangular inlet opening in generally sealing relation thereto andprojecting from the inlet frame toward the outlet frame in the assembledstate.

In another aspect, embodiments of the invention provide a filterassembly that includes an inlet frame having an inlet opening, an outletframe, a housing body extending between the inlet frame and the outletframe, first and second housing gaskets, the first housing gasketsealing between the outlet frame and the housing body, the secondhousing gasket sealing between the inlet frame and the housing body, andat least one filter having filter media installed in the inlet openingin generally sealing relation thereto and projecting from the inletframe toward the outlet frame in the assembled state.

In another aspect, embodiments of the invention provide a filterassembly that includes a filter housing assembly with an inlet framehaving a rectangular inlet opening, wherein the rectangular inlet framedefines a rectangular recess having a seating surface in surroundingrelation of the rectangular opening, and a V-bank filter (or otheralternative primary filter as disclosed herein) having an outerperipheral flange seated against the seating surface and extendingthrough the inlet opening into the housing assembly. The filter assemblyfurther includes a prefilter upstream of the V-bank filter and seatedagainst an upstream face of the outer peripheral flange, a rectangularwall of the inlet frame surrounding the rectangular inlet opening, aplurality of posts arranged around the rectangular wall, first retainerclips mounted on the rectangular wall in a first plane releasablysecuring the V-bank filter along the seating surface, and a secondretainer clips along the posts releasably securing the prefilter overthe V-bank filter.

In some embodiments and according to yet another aspect, the rectangularinlet frame may itself be directly mounted to a wall structure of anbuilding and thereby used as the housing for the primary filter and/orprefilter. The design is thus versatile allowing for fully enclosedhousings, or open housings to be employed.

According to this feature, a rectangular inlet frame has a plurality ofrectangular inlet openings, wherein the rectangular inlet frame definesa rectangular recess having a seating surface in surrounding relation ofeach rectangular inlet opening. The rectangular inlet frame can bemolded of material comprising plastic to further include at least onedivider grid to provide at least two of said rectangular inlet openings.A plurality of primary filters are installed into the rectangular inletopenings, each primary filter comprising at least one of a V-bank filterand a rectangular filter that includes filter media that is at least 3inches deep, each primary filter having an outer peripheral flangeseated along the seating surface with the primary filter extendingthrough the rectangular inlet opening. First retainers mounted on therectangular inlet frame releasably secure the primary filters along theseating surface.

The inlet frame can provide a unique method of servicing the filterassembly comprising: rotating first retainer clips to allow clearance toinstall the primary filter elements; installing the primary filterelements, one into each rectangular inlet opening; and thereafter,rotating the first retainer clips to secure the primary filter elementsin the rectangular inlet openings. Prefilters may optionally beinstalled with similar methodology and a different set of rotatableretainer clips.

When used in an animal confinement facility, the substantially plastichousing (e.g. most structural components, but not necessarily fastenersor retainers) provides an animal confinement facility including at leastone filter assembly. The combination comprises an animal confinementbuilding having a ventilation system with an air flow inlet; asubstantially plastic filter housing mounted inline with the air flowinlet to filter air flowing therethrough; and a primary filter mountedin the substantially plastic filter housing, the filter being at least aMERV 15 or higher and a filtration efficiency sufficient to preventtransmission of the PRRSV for filtering sub-micron sized viruses from anairflow stream flowing through the air flow inlet.

In still another aspect, embodiments of the invention provide a methodof assembly an air filter housing that includes providing an inletframe, an outlet frame, and a collapsed housing body having a generallyflattened state, erecting the housing body to a tubular shape adapted tomate with the inlet and outlet frames, fastening the housing body toeach of the inlet frame and the outlet frame, and mounting the housingto a building.

In yet another aspect, embodiments of the invention provide a method ofinstalling a filter assembly into an animal confinement building thatincludes installing a bottom housing panel over an air flow opening inthe animal confinement building, cutting the bottom housing panel tohaving an outlet opening matching the air flow opening, assembling anupper portion of the filter housing with the bottom housing panel, theupper portion including at least one inlet opening, and installing atleast one filter element into the inlet opening.

In yet another aspect, embodiments of the invention provide an animalconfinement facility including an animal confinement building having aventilation system with an air flow inlet, a substantially plasticfilter housing mounted inline with the air flow inlet to filter airflowing therethrough, and a primary filter mounted in the substantiallyplastic filter housing, the filter being at least a MERV 16 or higherand filtering sub-micron sized viruses from an airflow stream flowingthrough the air flow inlet.

Another aspect of the present invention is directed to a non-V-Bankfilter alternative to V-Bank filters that have been employed in thefiltration of PRRSV in hog confinement facilities. Preferably, deeppleating technology or in the alternative other self-supported media(e.g. such as fluted media packs having alternating face and flutedsheets as disclosed in U.S. Pat. No. 5,820,646) may be utilized. Mediais selected that has sufficient air flow characteristics, and with atleast a MERV 14 rating (preferably rated a MERV 15 or 16) and capabilityto filter the PRRSV virus at rated air flows experienced in animalconfinement applications.

Another aspect of the present invention is directed a more compactfilter element that can handle the air flow of a standard 12 inch headerV-bank filter. Testing has found that filter elements less than 12inches can be accomplished in some embodiments, more preferably lessthan 10 inches, and most preferably around 6 inches in depth. Comparablefiltration performance and air flow capacity is demonstrated in a filterelement package occupying about half the depth and thereby about onehalf of the volume. As filter banks occupy substantial envelope space inconfinement buildings, this more compact filter offers substantial spacesavings for animal confinement buildings. Further, this also saves onshipping costs of relatively bulky filters as twice as many filters canbe shipped in the same size freight, resulting in freight cost savingsof ½.

Alternatively 12 inch header depth may also be used in some embodimentsproviding for greater capacity, increased flow potential and/or longerfilter life. Fewer filters may be needed in systems employing largercapacity filters. In fact air flow benefits can be had with larger pleatpacks of 10 inches or greater. For example, for buildings demandinggreater air flows desires for the animal environment, even greater airflows can be achieved by replacing V-bank filters with certain deeppleated embodiments (e.g. pleats may be between 8-11 inches, or otherrange) in embodiments such as FIG. 11, and encompass these inventiveaspects. This is because the volumetric air flow advantage ofembodiments are substantial as compared to the V-bank (see e.g. FIG.38).

According to one aspect, a method of removing porcine reproductive andrespiratory virus (PRRSV) from an air flow stream into an animalconfinement facility, comprises: placing a filter element along the airflow stream to filter out PRRSV; arranging filter media in a frame toprovide the filter element, the filter media being in a non-V bankconfiguration; and having the filter media comprise: a MERV rating of atleast 14 and an efficiency sufficient to adequately filter the PRRSV;and an air flow of greater than 200 cfm @ resistance of 0.2 inch watergauge, per square foot occupied by the filter element transverse to theair flow stream.

Another inventive aspect is directed to a non-v-bank filter element withcertain PRRSV removal capabilities and a high air flow capacity. Thefilter element is adapted for filtration of porcine reproductive andrespiratory virus (PRRSV) from an air flow stream to an animalconfinement building, and comprises: a rectangular frame; a filter mediapack extending across the frame in a non-V-bank configuration, thefilter media pack having a depth of less than 8 inches such that incombination with the frame the filter element has a depth of less than10 inches in a direction perpendicular to a plane defined therectangular frame, the filter media pack comprising: a MERV rating of atleast 14 and a filtration efficiency sufficient to prevent transmissionof the PRRSV; and an air flow of greater than 200 cfm @ resistance of0.2 inch water gauge, per square foot occupied by the filter elementtransverse to the air flow stream.

Yet another aspect is directed toward a filter element that may be in anon-v-bank configuration with a high air flow capacity and a MERV ratingof at least 14. The filter element comprises: a support frame; a filtermedia pack comprising filter media extending across the frame and havingdepth of greater than about 3 inches, the filter media pack comprising:a MERV rating of at least 14; and a volumetric air flow capacity that isin excess of 500 CFM/cubic foot of filter envelope@ resistance of 0.2inch water gauge.

The filter element according to the above aspect may have one or more ofthe following features: a MERV 15 or 16 rating, and a filtrationefficiency sufficient to prevent transmission of the PRRSV; wherein thefilter media pack is a pleat pack having pleat flanks and pleat tips,and comprising adhesive spacers around pleat tips at at least one of theinlet and outlet faces, the spacer adhesively securing adjacent pleattips; embossments integrally formed into the pleat flanks; an air flowcapacity greater than 300 cfm @ resistance of 0.2 inch water gauge, persquare foot occupied by the filter element transverse to the air flowstream; the support frame being rectangular including a frame sidewalland a frame header extending outwardly around the sidewall to define alarger perimeter than the sidewall; a rectangular gasket along one sideof the frame header; a volumetric air flow capacity that is in excess of600 CFM/cubic foot of filter envelope@ resistance of 0.2 inch watergauge (and more preferably greater than 700); pleats extending a pleatdepth greater than about 3 inches and less than 11 inches, the pleatsbeing having embossments extending between pleat tips and adhesivespacer supports extending around pleat tips and connecting with adjacentpleat tips; a compact element (versus standard V-bank) wherein thefilter media pack has pleat depth between 4 inches and 8 inches; apleath depth of at least about 3 inches with synthetic polymeric fibersthat are heat set and embossed and have spacer supports between pleatflanks to provide structural integrity sufficient an air flow of greaterthan 300 cfm per square foot of filter element; a filter media compositewith a carrier layer and an efficiency layer, the efficiency layerhaving a higher filtration efficiency than the carrier layer andproviding for filtration of PRRSV, wherein the efficiency layercomprising a polymer with a hydrophobic additive (the efficiency layermay comprises polypropylene fibers with a fluorine additive); a filterelement span each way perpendicular to the air flow of between 20 and 48inches with adjacent pleat tips are spaced between about ½ and 2centimeter, and the pleat tips are flattened between about 1-3millimeters, the filter media being at least one of a MERV 15 and a MERV16; the filter media pack comprises a non-V-bank configuration, thefilter media pack being pleated or fluted.

Finally another inventive aspect is directed toward a filter system inan animal confinement building, which may comprise any of the filterelements described above. Such a filter system for filtration of air foranimals may comprise according to certain advantageous embodiments: afilter housing mounted to an animal confinement building, the animalconfinement building generating an air flow though the filter housing; afilter element installed into the housing in sealed relation, the filterelement including: a frame; a filter media pack supported by the framein a non-V-bank configuration, the filter media pack having a depth ofgreater than 2 inches and less than about 11 inches such that incombination with the frame the filter element has a depth of about 12inches or less in a direction perpendicular to a plane defined therectangular frame, the filter media pack comprising a MERV rating of atleast 14.

Other aspects, objectives and advantages of the invention will becomemore apparent from the following detailed description when taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of thespecification illustrate several aspects of the present invention and,together with the description, serve to explain the principles of theinvention. In the drawings:

FIGS. 1-3 are schematic views of negative pressure, neutral pressure andpositive pressure animal confinement buildings employing a filterassembly according to embodiments of the present invention;

FIG. 4 is an exploded isometric view of a filter housing assemblyaccording to an embodiment of the present invention;

FIG. 5 is an isometric view of an assembled filter housing assemblyaccording to an embodiment of the present invention;

FIGS. 6-9 show the progressive installation and assembly of a filterhousing assembly onto the truss structure of an animal confinementbuilding in accordance with an embodiment of the present invention, withFIG. 9 additionally illustrating the filter housing assembly incombination with pre-filter panel filter elements and V-bank filterelements in accordance with embodiments of the present invention;

FIG. 10 is an isometric view of a V-bank filter which may be used andinstalled into the filter housing assembly;

FIG. 11 is an alternative embodiment of a deep pleated primary filterthat can be used as an alternative to the V-bank filter according to anembodiment;

FIG. 12 is an isometric view of a panel pre-filter that can be used andinstalled in combination with a V-bank or other primary filter in thefilter housing assembly of the prior figure;

FIG. 13 is a cross sectional view of an overall filter assemblyincluding a filter housing assembly, a primary V-bank filter and a panelfilter according to an embodiment of the present invention;

FIG. 14 is a close up illustration showing how the pre-filter and V-bankfilter and corresponding seals are arranged relative to the inlet frameof the fuel filter assembly;

FIGS. 15-23 provide illukrations of two-filter and four-filterassemblies in various stages of assembly, in accordance with embodimentsof the invention;

FIG. 24 is an illustration of an exemplary vertical filtering wallinstalled in an animal confinement facility; and

FIGS. 25-31 provide illustrations of four-filter assemblies configuredfor use in filtering walls and shown in various stages of assembly, inaccordance with an embodiment of the invention.

FIG. 32 is a schematic illustration of an animal confinement facility,with a filter assembly constructed in accordance with an embodiment ofthe invention.

FIG. 33 is an isometric view of an embodiment of a compacted filterelement in accordance with an embodiment of the present invention thatcan be employed in the systems and housings of any of the priorembodiments.

FIG. 34 is a cross section of a portion of the filter element shown inFIG. 33.

FIG. 34 a is a cross sectional view of the filter element shown in FIG.34, but also enlarged and with the filter element installed in a filterhousing assembly that may be the same or similar (e.g. with shortenedsidewall) as that depicted in FIG. 13.

FIG. 34 b is an isometric cut-away illustration of a filter housing in atight eve space of an animal confinement building with the smallercompact filters situated therein.

FIG. 35 is an enlarged schematic plan view of two pleats along eitherupstream or downstream face of the pleat filter pack used in the filterelement of FIGS. 33 and 34 to better illustrate integral embossments inthe pleat flanks and bead spacers and supports that made be interposedbetween adjacent pleat flanks.

FIG. 36 is a schematic illustration of the synthetic filter mediaemployed in the filter pack of FIG. 33 showing a carrier layer and ahigh efficiency hydrophobic layer.

FIG. 37 is a performance graph comparison between a 6 inch deep pleatedor “flat” filter and a standard 12 inch deep V-Bank filter, thatillustrates the 6 inch deep pleated or “flat” filter has comparable airflow characteristics.

FIG. 38, is a similar performance graph as FIG. 37, but illustrates theairflow improvement relative to space occupied by the 6 inch deeppleated or “flat” filter over the V-Bank filter.

FIG. 39 is an isometric exploded view of a compact pleat filter assemblyaccording to an alternative embodiment of the present invention withdifferent height and width dimensions.

FIG. 40 is an assembled isometric view of the filter assembly of FIG.39.

While the invention will be described in connection with certainpreferred embodiments, there is no intent to limit it to thoseembodiments. On the contrary, the intent is to cover all alternatives,modifications and equivalents as included within the spirit and scope ofthe invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

Before turning to non-v bank embodiments, first description will be hadas to various preferred filtration systems and embodiments in whichV-bank filters may be employed, and in which the non-V-bank filteraccording to FIG. 11 or FIGS. 33-40 may be employed as substitute.Further, in any of these embodiments or others alluded to in otherpatent publications referenced, the housings therein and building spaceutilized may be modified to a shallower depth and more compact package,thereby as a significant space savings.

In accordance with various embodiments, a filter assembly 10 isschematically illustrated in animal confinement building environment inFIGS. 1-3. Different environmental configurations are shown in FIGS. 1-3for different buildings 12, 14 and 16 in FIGS. 1-3 respectively.

For example, in the negative pressure system and building 12 of FIG. 1,exhaust fans 18 are arranged on the outer walls of a building to suckand blow air out of the building, thereby creating a negative pressuredifferential on the inside of the building 12 relative to the outsideambient environment. A plurality of filter assemblies 10 may beinstalled such as in the roof and structure of such a building 12 asillustrated in FIG. 1., With holes cut in the roof corresponding toopenings and airflow inlets in the building, the filter assemblies 10are arranged over such inlet openings to filter the air entering thebuilding 12.

All references, including publications, patent applications, and patentscited herein are hereby incorporated by reference to the same extent asif each reference were individually and specifically indicated to beincorporated by reference and were set forth in its entirety herein.Specifically, the entire teachings and disclosure of Patent ApplicationNo. 61/490,896 (filed May 27, 2011), which discloses embodiments of aV-bank air filtration system such as for animal confinement facilities,are incorporated herein by reference thereto.

In the second environment and embodiment of FIG. 2, the filter assemblyis shown installed in a wall of the building 14 downstream of an inletblower 20, which exerts positive pressure on the filter assembly 10 toforce air through the filter assembly 10 and into the building 14.Building 14, however, is a neutral pressure having a similar or slightlydifferent pressure than the ambient environment as embodiment alsoincludes an exhaust fan 18 similar to the first embodiment to blow andexhaust air forcibly from the building. Depending upon the balancebetween the exhaust fan 18 and inlet blower 12 in the neutral pressurebuilding 14 of FIG. 2, either the same or slightly positive or negativepressure may be developed in the building relative to the outsideambient environment, but is considered to be a neutral pressureconfiguration due to both the inlet blower 20 and exhaust fan 18combination that attempts to maintain a relative true neutral pressure.

Yet a third environment and embodiment employs a positive pressurebuilding 16 in which filter assemblies 10 may also be installed into thewall of the building 16. In this embodiment, however, there is noexhaust fan means, but instead only inlet blowers 20 that take outsideair and forcible push air through the filter assembly 10 to create apositive pressure inside the building 16 that is greater than theoutside ambient environment. This higher pressure contained within thebuilding will cause any air pressure within the building to or flowthrough cracks to be from the inside to the outside. Typically, aone-way outlet such as a louvered outlet panel or other check valve typestructure is provided to allow for organized exhaust flow ventilation ofair from the inside to the outside of the building due to the higherpressure created inside of the building by virtue of inlet blower 20.

Now that various embodiments and environments for the filter assembly 10have been described, attention will now be drawn in greater detail tothe filter housing assembly 30 shown in greater details in FIGS. 4 and 5and also the overall filter assembly 10 which further includes a primaryfilter such as V-bank filters 32 (shown in FIG. 10) or a single-headerbox filter 100 (shown in FIG. 11), and panel pre-filters 34 (shown inFIG. 12) that are installed in combination with filter housing assembly30.

Referring to FIGS. 4 and 5, the filter housing assembly generallyincludes three primary structural components including a rectangularinlet frame 36, a rectangular outlet frame 38 and a housing body 40 thatis generally interposed between the rectangular inlet frame 36 and therectangular outlet frame 38 in an assembled state. The rectangular inletframe 36 defines at least one, and typically multiple rectangular inletopenings 42, which are adapted to convey and receive air into theoverall housing structure. The rectangular outlet frame may be formedwith a preformed hole or outlet opening as well, but in a preferredembodiment has a solid panel 44 (shown in FIGS. 7 and 8), which may thenbe cut to exact specifications to match the exact flow opening in thestructure of the animal confinement building as can be seen with laterreference to FIGS. 6 and 7 showing the custom cutting of such anopening.

An advantage of this particular design and embodiment is that it canallow or afford the ability to have a compact and flattened state forshipping and can easily be assembled on site. For example, the housingbody 40 is collapsible and has a flattened shipping state as shown inFIGS. 15 and 16. For example, the inlet and outlet frames 36, 38 may beformed of relatively rigid and stiff molded plastic material to providefor complex structures whereas the tubular housing body 40 may beconstructed of relatively thin, but sufficiently stiff when erectedplastic corrugated wall board material. Suitable materials for thehousing body include corrugated wallboard material from CarterAssociates, Inc., such as is commercially available or otherwise whichmay be used in containers such as those described in U.S. Patent Pub.No. 2005/0150812 (Carter), or U.S. Pat. No. 5,322,213 (issued to Carteret al.), or U.S. Pat. No. 5,351,846 (issued to Carter), the entireteachings and disclosures of which are incorporated herein by referencethereto. Other solid wall or multiply wallboard material or multi-plyplastic material may also be utilized.

This material may have six integral hinges 46, which may be provided ateach one of the four corners of the structure as well as optionally, anadditional two integral hinges 46 may be formed intermediate to the fourside panels 48 of the housing body 40. Thus, at least four integralhinges are provided to allow the housing body 40 to fold and collapse toa substantially flattened state to reduce the shipping volume andthereby shipping cost. When erected, however, a relatively stiffstructure is provided by virtue of the stiff nature of the corrugatedplastic wall board material used in the housing body 40. Additionally,provided as part of the housing assembly 30 is an upper gasket 50 and alower gasket 52, which may be large rectangular rope gaskets each. Theseeach get installed and compressed axially between the housing body 40and the rectangular inlet frame and rectangular outlet frames 36, 38,respectively, when the housing assembly 30 is fully assembled.Typically, these will be compressed around 20-30% when installed andprovide a sealed box-like enclosure so that unfiltered air is forcedthrough the inlet openings 42 and eventually through the outlet opening54 which is eventually cut into the solid panel 44 of the rectangularoutlet frame 38.

In an embodiment and an optional, but preferred feature, is also the useof a plurality of snap fasteners, which may take the form of snapbuttons 58 that are installed, preferably onto the housing bodyproximate the upper and lower edges of the side panels 48 for snap fitinto corresponding mounting holes 60 formed into the inlet and outletframes 36, 38 as illustrated. While FIG. 4 shows exploded assembly viewof the snap buttons 58 for illustration purposes, it will be understoodthat typically the snap buttons 58 will be fully installed and assembledat the factory such that these structures do not need to be assembledonsite. The snap buttons 58 may include a screw, or bolt, 62 and a snapbutton projection 66 that has an enlarged and flexible head that can bepress fit through a corresponding mounting hole 60 and has a resilientlyflexible nature to flex outward and form an enlarged head, larger thanthe mounting hole 60 to prevent dislodgement therefrom.

During assembly, the side panels 48 of the housing body 40 will beerected into a rectangular and tubular shape and then the housing bodywill pressed onto the lower gasket 52 on the lower outlet frame 38 untilthe snap buttons 58 are received into the corresponding mounting holes60 formed around the perimeter of the outlet frame. Thus, the housingbody 40 is received into the periphery of an L-shaped bracket portion 68of the outlet frame 38 with the lower gasket 52 fitting on a sittingrecess formed by that L-shaped bracket portion 68. With the snap buttons50 received in the mounting holes 60, the lower gasket 52 is maintainedin a state of compression, thus causing a sealing relationshiptherebetween.

Similarly, for the inlet frame 36, there is an L-shaped bracket portion72 with an seating recess 74, which also receives upper gasket 50. Withthe housing body 40 already attached to the outlet frame, the inletframe may now be situated and received onto the other edge of thehousing body 40 with upper gasket 50 compressed therebetween again untilthe snap buttons 58 are received into the corresponding mounting holes60 of the inlet frame 36, which run again around the periphery of theinlet frame 36. Again, the housing body 40 is thus received into theinner periphery of the L-shaped bracket portion 72 (shown in FIG. 14) ofthe inlet frame 36 with the upper gasket 50 maintained in a state ofcompression when the snap buttons 58 are received in the mounting holes60 thereby providing again a sealed relationship between the housingbody 40 and the inlet frame 36.

On the side opposite the L-shaped bracket portion 72 (shown in FIG. 14),the inlet frame 36 defines structure for receiving and mounting thefilter elements, which may include the primary filter such as. V-bankfilter 32 and panel pre-filter 34. In particular, the exposed side ofthe inlet frame includes preferably grid work 76 (shown in FIGS. 4 and5) to divide the inlet space into a plurality of smaller inlet openings42. Surrounding each smaller rectangular inlet opening 42 is arectangular seating surface 80, which is in turn surrounded by arectangular wall 82. Further, a plurality of posts 84 are arranged atdifferent locations around the rectangular wall 82 to provide for anelevated plane. These posts 84 may be provided, for example, at thecorners of the rectangular wall structure.

Additionally, a first set of retainer clips 86 are mounted on therectangular wall 82 in a first plane for releasably securing the V-bankfilter 32 along the seating surface 80. Further, a second set ofretainer clips 88 are provided along the posts 84 and arranged in asecond plane for releasably securing the pre-filter 34 over the V-bankfilter 32. Again, the clips 86, 88 while shown for purposes ofillustration in FIGS. 4 and 13 as unassembled would typically beassembled and installed at the factory rather than onsite. Each clipmay, for example, include a screw 90 and a clip body 92 (shown in FIG.13) and have a compression portion 94 (shown in FIG. 13) that is movableover the rectangular recess 96 (shown in FIG. 13) that is formed byvirtue of the seating surface 80 and rectangular wall 82. In thismanner, the compression portion 94 may be moved over and into engagementto retain and preferably compress the filter toward the inlet frame 36.In the case of the V-bank filter 32, the first retainer clips 86 serveto compress seal between the V-bank filter 32 and the inlet frame 36 toensure a sealing connection therebetween.

To the extent not clear from the foregoing, it can be noted that thefilter housing assembly 30 may be configured to have either one inletopening 42 or a plurality of inlet openings 42 and all of the claimsappended hereto are broad enough to include both possibilities. Forexample, a relatively small and compact filter unit may be provided withone rectangular opening. Typically, at least two and as shown, morepreferably four or more inlet openings 42 are provided to respectivelyreceive four or more respective V-bank filter 32 elements and panelpre-filter 34 elements.

Now that some attention has been provided to the filter housing assembly30, additional attention will be directed toward the primary andpre-filters, which may be used in combination therewith and therebyprovide for the overall filter assembly 10. Referring to FIGS. 10 and 11are alternative embodiments of a primary filter showing the V-bankfilter 32 or alternatively a single-header box filter 100 where it is ineffect, a deep pleated panel filter having a depth of at least about 10inches for most typical applications. FIG. 11 illustrates an exemplarysingle-header box filter 100, such as might be used in theaforementioned Micro Guard ® LR filter. The box filter 100 includes cellsides 188, which in at least one embodiment, are made from a rigidmaterial, including plastics, such as high-impact polystyrene, or metal.

In a particular embodiment, a flange 190, made of the same material asthe cell sides 188, is attached on a front side of the single-header boxfilter 100 around the perimeter of cell sides 188. In a particularembodiment, the media is molded into pre-formed channels that form thepleats. A pleated media pack 192 is attached, using an adhesive forexample, on interior surfaces of the cell sides 188. In at least oneembodiment, the media pack includes embossed pleats and is made from asynthetic, water-resistant material whose performance is substantiallyunaffected, other than a temporary rise in airflow resistance, byhumidity and exposure to moisture levels reasonably expected to be foundin airstreams in animal confinement facilities.

Referring back to the V-bank filter 32 of FIG. 10, it can be seen thatthe V-bank filter 32 includes an outer peripheral border frame 102providing an outer peripheral flange 104 that is rectangular and sizedto be received and seated within the rectangular recess 96 (shown inFIG. 5) of the filter inlet frame 36 of filter housing assembly 30.Solid side panels may be on either side of the frame and inlet andoutlet bridge sections 108 may traverse between side panels 36. Inaddition, a plurality of individual pleated filter elements panels 110provided in V-shaped pairs with each element extending along an anglebetween adjacent inlet side and outlet side bridge sections 108. Atleast one pair and typically two or more pairs of pleated filterelements panels 110 arranged in V-bank configuration are provided inV-bank filter 32. Additionally, a downstream gasket 112 is preferablyprovided on the downstream side of the border frame 102 and morespecifically the flange 104 to be compressed between the V-bank filter32 and the seating surface 80 of the inlet frame 36 when seated andcompressed thereto to thereby provide for sealing relationship betweenthe V-bank filter 32 and the inlet frame 36. This prevents unfilteredairflow from bypassing the V-bank filter 32.

Additionally, preferably there is an upstream rectangular gasket 114provided on the flange 104 on the side opposite the downstream gasket112 to provide for an eventual approximate seal between the panelpre-filter 34 and the V-bank filter 32. This relationship and sealingsituation can all be seen, for example, in FIGS. 13 and 14 with someadditional details illustrated at least in part schematically. A toppanel 153 and bottom panel 155 (also referred to as end panels) coverthe top and bottom portions, respectively, of the V-bank filter 32, andthe panels 153, 155 create a seal with each of the panel filters 140such that air flowing into the V-bank filter 32 must flow throughpleated filter elements panels 110. It is also contemplated thatnon-pleated filter panels may also be used to construct the V-bankfilter element 138, such as a collection of other panel filters arrangedin a V-bank configuration.

In at least one particular embodiment of the invention, the V-bankfilter 32 uses a MERV 16 filter media 147 (shown in FIG. 5). In analternate embodiment, the V-bank filter element 32 uses a MERV 15 filtermedia, as determined by the ASHRAE 52.2-2007 standard. In anotheralternate embodiment of the invention, a HEPA filter may be used as theV-bank filter media. A HEPA filter is configured to capture 99.97 of allparticles of 0.3 micron in size. Additionally, a near-HEPA filter, suchas that sold under the brand name Micro Guard® LR, which combines lowresistance to airflow with efficiencies above 99% for 0.3 micronparticles may be used in a single-header box filter 100 in place of theV-bank filter 32.

To understand why these filter medias are effective at trapping airborneviruses affecting agricultural livestock, it helps to know the particlesize of some typical viruses. For example, there are severalswine-specific disease agents that affect pigs and hogs in animalconfinement facilities, such as mycoplasma whose particle size typicallyranges from 0.3 micron to 0.9 micron. Other swine-specific diseaseagents include the swine influenza virus whose particle size typicallyranges from 0.080 micron to 0.120 micron, the porcine reproductive andrespiratory syndrome virus (PRRSV) whose particle size typically rangesfrom 0.050 micron to 0.065 micron, and the porcine circovirus type 2(PCV2) whose particle size typically ranges from 0.0017 micron to 0.0022micron. Due to the small particle size of these viruses, high-efficiencyfilter medias are needed to filter these particles from the air, or fromthe small particles that carry these viruses through the air.

Referring to FIG. 12, the upstream panel pre-filter may include asingle-pleated card of filter media between ½ inch and 3 inches deepwith the filter media indicated at 116. This filter media at 116 may besurrounded by a paper board border frame 118. Similar to the V-bankfilter 32, the single-header box filter 100 would be used with a panelpre-filter 32 to remove large particulates and other contaminants thatcould clog or otherwise impair the performance of the single-header boxfilter 100. Typically, pre-filters 34 used with box filter 100 such asthe Micro Guard® LR filter will have efficiencies of MERV 8 or higher.

Installation of the primary V-bank filter 32 is first with the firstretainer clips 86 used to secure the V-bank filter in place and compressthe at least the downstream gasket 112 against the seating surface 80 ofthe inlet frame 36 of filter housing assembly 30. Then, the panelpre-filter 34 may be installed and retained by the second retainer clips88, again by rotating the retainer clips to include a retainer portionover the outer border frame 118 of the panel filter. In use, the V-bankfilter 32 as well as the panel pre-filter 34 may be conveniently removedwhen spent and replaced with new fresh filter elements periodicallyafter the filter life is spent.

Turning again to FIGS. 6-9, a preferred method of initial installationis described in association with a wall structure 120 of an animalconfinement building. It is understood that the wall structure 120 maybe a vertical wall, a horizontal wall or other such wall structureincluding various roof structures or rafter structures including rafterstructures within such roofs. Turning to FIG. 6, the rectangular outletframe 38 with the initial solid panel 44 is illustrated and can be fitin association with an airflow opening 122 formed in naturally oroccurring in the wall structure 120 of the animal confinement building.From that, the technician may custom cut the outlet opening 54 to matchand correspond to the size of airflow opening 122 in the wall structurewhich can be seen in FIG. 7. The technician may then securely fasten,such as bolting or screwing the outlet frame 38 to the boards 120 ofwall structure 120.

Turning then to FIG. 8 in with the appropriate upper and lower gaskets50, 52 seated in the respective inlet and outlet frames 36 and 38, theerected tubular housing body 40 can then be snapped onto and intofitting relation with the outlet frame 38 via the snap buttonspreviously described. This places the lower gasket 52 into compressionand sealing relationship between the housing body 40 and the outletframe 38. The inlet frame, can similarly be situated on the other sideof the housing body 40 again with the snap buttons securing the inletframe 36 to the housing body 40 and causing compression and sealingrelationship therebetween by virtue of upper gasket 50.

FIGS. 15-23 provide illustrations of two-filter and four-filterassemblies in various stages of assembly, in accordance with embodimentsof the invention. However, as stated above, it is envisioned thatalternate embodiments of the invention include one-filter assemblies,eight-filter assemblies, and other filter assemblies of different sizes.The assembly process should be very similar for a filter assembly,regardless of the size.

FIGS. 24 and 32 illustrate another way in which filters may be employedin animal confinement buildings 250. In many animal confinementbuildings 250, air is forced through banks of vertical evaporative coolpads 252 reduce the temperature inside the building 250 during the warmsummer season, for example. These evaporative cool pads 252 aretypically configured as a vertical wall in which water, circulated by apump 254, continually flows from top to bottom. The evaporative coolpads 252 are generally located at one or both ends of the building 250,and large perimeter exhaust fans 256 push (or pull, depending on thelocation of the fan) the air through the evaporative cool pads 252 andinto the building 250 such that the water flowing through theevaporative cool pads 252 decreases the air temperature.

In some cases, prior to the air flowing through the evaporative coolpads 252, it must flow through a filtering wall 260, an example of whichis shown in FIGS. 24 and 32. These filtering walls 260 may include aV-bank filter 32 (shown in FIG. 10), or single-header box filter 100(shown in FIG. 11), used in combination with a panel pre-filter 34(shown in FIG. 12). Conventional filtering walls may includeinterlocking metal frames, between wall studs, which use wire clips tohold/retain the filters. The installation of these filtering walls, isoften a costly and time-consuming tasks involved with the retrofittingof an existing animal confinement facility with the aforementionedcooling system.

FIG. 25 provides an illustration of the four-filter plastic inlet frame36 configured for installation in an animal confinement facility within,for example, the structural wood framing of an animal confinementbuilding 250. In the embodiment of FIG. 25 and in the following figures,the plastic inlet frame 36 is used in a filter assembly as the filterhousing by itself in that it does not include the remainder of thehousing components shown in the embodiments described above. As can beseen from the example of FIG. 25, instead of being assembled, theplastic inlet frame 36 is used as the housing by being inserted betweensimulated adjacent wall studs 204 on each side. Simulated cross-bracing206, assembled between simulated adjacent wall studs 204, borders theplastic inlet frame 36 on the top and bottom. In the embodiments shown,the simulated wall studs 204 and cross-bracing 206 are made from wood,though it is contemplated that the framing for the animal confinementbuilding 250 could be made from other materials, including, but notlimited to, plastics and various types of metal suitable for structuralmembers. The seal 208 between the plastic inlet frame 36 and the woodenstuds 204 and cross-bracing 206 can be provided by a bead of caulkaround the perimeter of the plastic inlet frame 36, or, alternatively,by an inlet frame gasket. For example, a peel-and-stick gasket may beapplied to the wall studs 204 and cross-bracing 206 to provide thesealing surface. In an alternate embodiment, the inlet frame gasket 208could be assembled to the plastic inlet frame 36 before assembly to thestructural frame of the animal confinement building 250. Screws can beinserted into the plastic inlet frame 36 and screwed into the woodenstuds 204 and cross-bracing 206 to secure the plastic inlet frame 36 inplace.

FIG. 26 provides a close-up view of the rotatable clips 86 used toretain the V-bank filter 32 (shown in FIG. 10) or single-header boxfilter 100 (shown in FIG. 11). FIG. 27 provides a close-up view of therotatable clips 88 used to retain the panel pre-filter 34 (shown in FIG.12), and keep that the panel pre-filter 34 is in sealing engagement withV-bank filter 32. FIGS. 28-30 illustrate the plastic inlet frame 36 witha one or more V-bank filters 32 installed. In a particular embodiment,the V-bank filters 32 each have the downstream gasket 112, attached tothe downstream side of the V-bank flange 104, to seal the V-bank filter32 to the plastic inlet frame 36, and the upstream gasket 114, attachedto the upstream side of the V-bank flange 104, to seal the panelpre-filter 34 to the V-bank filter 32. Each V-bank filter 32 is retainedby four rotatable clips 86 located approximately at the mid-point ofeach side of the V-bank filter flange 104. The rotatable clips 86 alsomaintain sealing engagement between the V-bank filter 32 and the plasticinlet frame 36. In the embodiment shown, the plastic inlet frame 36 is afour-filter assembly configured to hold two 24″×24″ V-bank filters 32 orsingle-header box filters 100 and two 24″×20″ filters. In alternateembodiments, the plastic inlet frame 36 is configured to hold four24″×24″ filters 32, 100 such that the plastic inlet frame 36 isapproximately four feet by four feet.

Thus, a filtering wall 260 approximately eight feet tall would include arow of plastic inlet frames 36 configured to hold and house four 24″×24″filters 32, 100 and stacked two high. In such an arrangement, the wallstuds 204 and cross-bracing 206 in the animal confinement building 250would each be spaced approximately four feet apart to accommodate andsupport the row of plastic inlet frames 36. It is also envisioned that aplastic inlet frame could be configured to hold two, six, or eight24″×24″ filters 32, 100. In a particular embodiment, the eight-filterassembly would gave four vertical openings and two horizontal openings.In this fashion, the plastic inlet frame 36 could still be insertedbetween wall studs 204 spaced four feet apart, but one plastic inletframe would extend from floor to ceiling eliminating the need for someof the cross-bracing 206 needed with the four-filter assembly.

It can be seen that embodiments of the invention allow for relativelyquick, simple installation and assembly of filtering walls 260. Theplastic inlet frames 36 are configured for relatively quick andair-tight assembly to existing wood-frame construction in animalconfinement buildings 250, such assembly requiring a few screws andeither caulk or a sealing inlet frame gasket 208. No tools are requiredto install the V-bank filters 32, or alternatively single-header boxfilters 100, or the panel pre-filters 34.

The plastic inlet frame 36 can be made from a variety of plasticmaterials, including but not limited to, new or recycled ABS,high-impact polystyrene, high-density polyethylene, high molecularweight polyethylene. The plastic inlet frame 36 is corrosion resistantand is well-suited for high-moisture environments, such as animalconfinement buildings 250 that employ evaporative cooling pads forcooling. In particular embodiments, the plastic material used is moldedplastic (e.g., injection-molded plastic) and includes a UV-inhibitor onthe exposed surfaces.

FIG. 31 illustrates the plastic inlet frame 36 with a one or more panelpre-filters 34 installed. Each panel pre-filter 34 is retained by fourrotatable clips 88 located at the four corners of each opening in theplastic inlet frame 36 and therefore at each corner of the panelpre-filter 34.

Turning to FIGS. 33-38 a further embodiment is shown depicting a morecompact filter element 410 for the filtration of PRRSV. According tothis embodiment, the outer height and width dimensions can be the sameas per a V-bank filter (e.g. the standard size in many applications is2′×2′). However, the depth of this embodiment can be considerably less,preferably less than 10 inches, more preferably less than 8 inches, andtypically about 6 inches as shown in this embodiment, or even less than6 inches. “About” is used to encompass rounding as fractions can berounded up or down and fall within the about range; and that it is knownthat actual size in filtration applications are often off a smallfraction from the listed dimension.

This embodiment can be employed and used in any of the housings andsystems of the prior embodiments, or those animal confinement filtrationsystems in aforementioned patent publications that have been referenced,even those with 12 inch deep filter envelope regions. Simply by usingthis filter, considerable cost savings in freight shipment alone aresignificant given the fact that air filters are large and occupyconsiderable space. It can be seen that the filter element 410 alsoincludes a common interface frame header that is received and mounts inany of the housings previously noted.

Additionally, any of the housings and systems of the prior embodiments,or those animal confinement filtration systems in aforementioned patentpublications that have been referenced can be built with a muchshallower depth by decreasing dimension of the housing sidewall by about6 inches. Housings that do not have sidewalls but a border frame a wallof a confinement building equally benefit as the envelope depth neededin the wall of the building is decreased as well. In either event, withbanks of these filters being employed and occupying considerable spacefor air flow, significant space savings in the building can be realized.

In one embodiment, the filter element has a height H dimensional span of2 feet or 24 inches and a width dimension span of 2 feet or 24 inches.Each of these dimensions H and W are perpendicular and transverse to thedepth dimension D (which is preferably about 6 inches or less). Depthdimension D is also the path along with the air flow travels through thefilter element 410.

Alternatively, deeper pleats to provide a filter element depth of 12inches or more may be employed with the filter 100 such as shown forexample in FIG. 11. With this arrangement, greater capacity for a givenvolume is realized, such that fewer filter elements in a bank may benecessitated, and/or greater capacity or filter lifespan can berealized.

Returning to FIG. 33, the filter element 410 includes a rectangularplastic frame 414 that includes a rectangular frame header 412 andrectangular depending sidewall 416. Upstream and downstream rectangulargaskets 418, 420 may be mounted to upstream and downstream faces of theheader 412 so that the filter element seals against the correspondinghousing sealing surface (for example the rectangular recess 96 shown inFIG. 13 that is formed by virtue of the seating surface 80).

Situated in the frame is a rectangular pleated filter media pack 422.The media pack may have the sides glued and sealed to the sides of theframe 414 by urethane 424 or other sealant/bonding agent that lines theinside of the frame 414 as shown in FIG. 34 in surrounding relation ofthe media pack 422.

Preferably, the upstream face of the media pack is recessed with theframe 414 as shown. In certain embodiments, and referencing FIG. 34 a,an upstream face of the filter media is recessed a distance R from anupstream face of the rectangular frame or from an upstream face of agasket along the upstream face of the rectangular frame by at leastabout ½ inch sufficient to provide a mixing chamber 428 sufficient toprevent blinding by an upstream prefilter 34 that may be the samepleated panel filter as that previously referenced. This is believed toprevents turbulence between the two filter elements in the “mixingchamber” 428 between the filter element 410 and the prefilter 34.Instead a more laminar flow is believed to develop to more orderlydevelop air flow through the assembly and medias for filtration. Thedistance R can also be accommodated by spacers employed in the housingsuch that the distance R may be accommodated by the housing with lesserrecess provided in the filter element 410. In either event, theprefilter 34, is spaced from the filter media pack 422 by at least about½ inch. As a result, the pleat pack may be between ½ and an inch lessthan the depth of the filter element, for example about five inches insome embodiments for a 6 inch deep filter. If the offset is providedelsewhere, a flush filter pack with the frame may be employed furtherreducing the size of the filter element under 6 inches.

As can also be seen in FIG. 34 a, the filter element can be used in ahousing assembly 430 that can be the same housing assembly shown in FIG.13 (or other such housing disclosed), and can be modified to include ashortened housing sidewall such that the overall housing can beshortened by 6 inches or other appropriate shortening depending upon thedepth of the filter element 410.

Another embodiment is shown in FIG. 34 b, in which a novel eve mountconfiguration is provided for the compact shallower depth filter element410. In particular, a hog confinement building 500 has a roof 102 thatoverhangs vertical wall 106 providing an eve 104 with limited space. Inaccordance with certain embodiments, a filter housing 108 comprises onlythe inlet frame 36 in this embodiment mounted to an underside of an eve.Compact or shortened filter elements 410 enable this location given thelimited filter envelope space available. This also saves on availablespace and serviceability in the hog confinement building 500 as thefiltration can be located in the eves.

To better facilitate for structural integrity and high air flow, somepreferred embodiments may include additional pleat supports and spacersbetween adjacent pleat flanks 434. For filter elements configured tooperate in high-flow-rate environments, spacers, such as plastic fingerspacers or hot-melt adhesives spaced at regular intervals, may be placedat regular intervals along the pleated filter media to add structuralrigidity and prevent deformation of the media. In addition to beingpleated with heat setting of the pleats, the filter media may also beembossed to add structural rigidity, to further increase surface area,and to increase amount of media that can be manipulated into a volumefor the filter element 410 and deep pleats. A method of embossed filtermedia is described in U.S. Pat. No. 6,685,833. U.S. Pat. No. 5,290,447,U.S. Pat. No. 5,804,014, and DE 19755466 A1 also describe methods ofembossing that, in some embodiments, may be applied to the compositefilter media of the present invention. Each of these patents areincorporated by reference in their entireties, as these or otherpleating and embossing technologies may be used.

For example, integrally formed embossments 438 (grooves, folds orwrinkles extending between pleat tips 435 and between inlet and outletfaces) formed into the filter media and adhesive spacer beads 436 areillustrated on the filter media of filter media pack 422 as shown inFIGS. 34 and 35. Various numbers and arrangements of embossments can beprovided. The adhesive beads are on adjacent pleat tips and extend alongpleat sides and attach to each other as shown. This provides consistentpleat spacing and structural integrity to the pleated filter pack. Theseare particularly advantageous for the deep pleats contemplated herein.Adjacent pleat tips may be spaced between ½ and 2 centimeter to compacta substantial amount of filter media into the envelope while at the sametime keeping an open flow structure to accommodate high air flowcapacity. Also, the peat tips may be flattened with two creased edges440 and a flat 442 therebetween as schematically illustrated in FIG. 35.Flats 442 may between 1-3 millimeters wide in some embodiments.

Other Non-V Bank filter media packs are contemplated. For example,fluted filter media that is self supporting and has alternating flutedsheets and facing sheets with alternating flutes closed proximateopposed ends such as shown in U.S. Pat. No. 5,820,646 are contemplatedas an alternative to the pleated media pack 422 and may be substitutedin some embodiments. As such, U.S. Pat. No. 5,820,646 is herebyincorporated by reference in its entirety.

Filter Media useable in any Embodiments Disclosed Herein

The filter media may have MERV rating of at least 14 and an efficiencysufficient to adequately filter the PRRSV. Most preferably at least aMERV 15 or 16 is provided. The media is relatively open to air flow andpermeable with an air flow of greater than 200 cfm @ resistance of 0.2inch water gauge, per square foot occupied by the filter elementtransverse to the air flow stream.

A variety of filter medias are known including cellulose and micro-glassfibers. While these may be used alone or in combination, certainpreferred embodiments include synthetic fibers and preferably melt blown(and/or electrospun) provide for heat setting, high permeability andefficiency. In one embodiment one or more efficiency layers arelaminated to a synthetic carrier layer. Example materials may bepolypropylene and polyester, however nylon, pvc or other polymers may beselected, including fluoropolymers and fluororesins. The filter media ispreferably an electret. Preferably a hydrophobic additive such asfluorine is added to the polymer by plasma fluorination such asdescribed in Ogale, U.S. Pat. No. 6,419,871, the entire disclosure ofwhich is hereby incorporated by reference. Other fluorination andadditives that may be alternatively added are described in Rousseau etal., U.S. Pat. No. 5,908,598 and Eitzman et al., U.S. Pat. No.6,406,657.

The fluorination of the media (addition of fluorine atoms into thepolymer) create special benefit of a hydrophobic property. This isenvisioned to cause special benefit as the inventors hereto haverealized that PRRSV transmission typically occurs at a high relativehumidity RH environments, typically exceeding RH 70. It is theorizedthat humidity or mist may be a carrier. As such the ability to keep outmoisture that may carrier virus may be desired.

To provide for an open pore structure for flow while at the same timeproviding efficiency, a composite filter media 444 is preferredaccording to some embodiments. For example a synthetic polyester carrierlayer 446 (e.g. a scrim or spun bound) may have a high efficiencypolypropylene layer 448 laminated to it, preferably on the upstreamside. The efficiency layer has substantially smaller fibers that may be2-20 times (or more in the case of nanofibers) smaller than the coarserfibers of the carrier layer. The carrier layer provides for support andpleatability, while the efficiency layer establishes the particlecapture efficiency of the media. A two layer composite 444 may beemployed in one embodiment, although 3 or more layers may be employed.While thicker medias can be provided a thinner less obstructive medialess than 1 millimeter in thickness is in some embodiments. Fewer layersare typically desired so as to prevent resistance to air flowconsidering the high air flow demands required in animal confinementbuildings.

To provide for adequate flow capacity, an air flow of greater than 200cfm @ resistance of 0.2 inch water gauge, per square foot occupied bythe filter element transverse to the air flow stream for the filterelement 410 alone. More preferably an air flow of greater than 300 cfm @resistance of 0.2 inch water gauge (and most preferably greater than 350cfm), per face area occupied—i.e. square foot occupied by the filterelement transverse to the air flow stream for the filter element 410alone. In an example for a standard 2′ high by 2′ wide filter, an airflow of greater than 800 cfm @ resistance of 0.2 inch water gauge isprovided (e.g. with a prefilter added, an example has greater than 1000cfm @ resistance of 0.2 inch water gauge as shown in FIG. 37.

For the volumetric envelope, benefit can be achieved. For example,airflow per filter envelope (airflow CFM/cubic foot of filter envelope)can be in excess of 400 and even preferably in excess of 500 @resistance of 0.2 inch water as demonstrated in FIG. 38 when employed incombination with a prefilter. Without the prefilter (e.g. the filterelement 410 alone), airflow per filter envelope (airflow CFM/cubic footof filter envelope) can be in excess 500, more preferably in excess of600 and most preferably in excess of 700.

With this, a variety of filter elements less than 12 inches in depth canbe achieved resulting in a smaller envelope and savings on freight cost.For example, filter elements less than 10 inches, more preferably lessthan 8 inches and most preferably 6 inches or less can be achieved.

However if there is adequate depth or insufficient face area forfilters, and greater air flow is desired deeper pleated of otherself-supported filter elements (such as FIG. 11) may be employed withfilter pack depths up to 11 inches of pleat depth or even more. Theseembodiments will provide even greater air flow as the volumetric airflow benefits illustrated in FIG. 38 demonstrate.

Turning to FIGS. 39 and 40, an alternative embodiment of a filter systemassembly 610 comprising a filter housing 612, a non-v-bank pleatedfilter element 614 and a prefilter 616 are illustrated. The filterelement of this embodiment is the same as the prior filter element withthe same pleat pack, embossing and adhesive spacers as the embodiment ofFIGS. 33-34, except that the dimensions are different. In particular,this illustrates an element that is 27 inch wide by 47 inches tall; andwith a depth of 6 inches (fractions being rounded). The prefilter 616has similar height and width dimensions. Also as can be seen a differenthousing 612 is provided, with a surrounding sidewall and ring clips thatsecure the filter assembly together.

It is contemplated that for many embodiments for animal confinementfacilities, the range of height and width dimensions will be between 20and 48 inches.

Standards for PRRSV Efficiency Removal

In the Swine industry, it is published and known (Dr. Dee, SDECresearch—Swine Disease Eradication Center, University of MinnesotaCollege of Veterinary Medicine) that a “Log 6 efficacy” device is thepreferred filtration level to prevent all animalcontraction/transmission of PRRSv and Mycoplasma hyopneumoniae (Mhyo).It is noted for example Devine et al., US 2009/0301402, refers to PRRSVtesting conducted by Dr. Dee at SDEC. Basically, the filter needs toremove the airborne microorganism concentration to a level of1/1,000,000. All lab tests and field trials have confirmed that animalsin a Log 6 or less concentration of PRRSV will not contract the virus.Field trials have also been done that support a Log 4 ( 1/10,000)filtration device is the absolute minimum requirement to prevent “most”transmissions; however, depending on other animal health/immunityissues, the animals have still contracted PRRSV in a Log 4 environment.

Therefore a most preferred embodiment should pass the Log 6concentration, and any embodiment should at least pass a Log 4concentration. As SDEC has established the standards for PRRSV removal,testing and test standards established by the Swine Disease EradicationCenter, University of Minnesota College of Veterinary Medicine are usedto establish log scale results, which can be done to evaluateperformance.

Generally, at least a MERV 14 and more preferably MERV 15 or 16 filtercan satisfy these log scale testing standards for PRRSV.

The other advantage of using the PRRSV testing standard is that thePRRSV is a quite small virus, and thus the PRRSV testing standard is ahigh standard. The filter is equally effective for Mycoplasmahyopneumoniae (Mhyo). It is also therefore contemplated for other viruscontrol applications in livestock where viruses can cause problems. Forexample it may be used for swine flu, foot and mouth disease for hogs orother type of livestock, or potentially for the new castle virus inpoultry applications. As such, claims limitations pertaining to PRRSVsufficiency (meeting the SDEC testing standard) merely set forth a passstandard for the filter element. Many certain filter element claims aretherefore broader in scope and not limited only for the application tocontrol PRRSV and can apply to other sorts of animal confinement andapplication. Methods of use directed to preventing PRRSV in swinefacilities are however so limited.

EXAMPLE

A 6 inch deep filter element with embossed pleats and adhesive bedseparators on the pleat tips was constructed generally in accordancewith the illustrated embodiment of FIG. 33. It occupied 4 square feettransverse to flow (2 foot high, by 2 l foot wide).

The pleated filter media chose was a T-LAM Grade SWI16 from TranswebLLC, sold under the brand TM230PXZPN/LY50. This media is generally ameltblown (25) polypropylene that is plasma fluorinated and laminated toa polyester (50) substrate with the following reported targetcharacteristics: basis weight 55 g/sq. m.; thickness 0.85 mm; airpermeability 115 crm @ 0.5″ water gauge; 1.5 mm/water gauge resistance;4% penetration (filtration testing on a TSI-8130 with 100 cm/2 sampleholder; challenge aerosol being NaCl at a face velocity of 5 cm/sec).The filter media had a MERV 16 rating.

PRRSV challenge testing conducted according to the above standards ofSDEC established better than a log 6 result demonstrating efficacy ofremoving PRRSV sufficient to prevent disease transmission. Test resultsare shown in table 1 below with comparison to a HEPA filter.

TABLE 1 6″ Depth-Flat Filter Treatment Controls PRRSV challenge MERV 16No filter HEPA log 9 10/10 pos  10/10 pos 0/10 pos log 7 0/10 pos 10/10pos 0/10 pos log 6 0/10 pos 10/10 pos 0/10 pos log 5 0/10 pos 10/10 pos0/10 pos log 4 0/10 pos 10/10 pos 0/10 pos log 3 0/10 pos 10/10 pos 0/10pos

Given the substantially high performance, a MERV 15 or MERV 14 iscontemplated as well to perform well for the PRRSV challenge.

Additionally, an air flow and resistance comparison (air flow)comparison was made between a 12 inch deep V-Bank and a 6 inch deepfilter element as described above in this example. Each had an upstream2″ deep pre-filter—a standard panel filter (Airguard DP® 40 MERV 8pre-filter). As can be seen, quite comparable air flow characteristicswith almost the same air flow capacity for a given resistance isprovided as demonstrated in FIG. 37. Further, when the filter envelopeor volumetric considerations are considered, the 6 inch deep filterelement has substantial benefit over the V-bank as demonstrated in FIG.38.

It should be noted that in FIGS. 37 and 38, the prefilter is used. Theair flow characteristics of the 12 inch deep V-Bank and a 6 inch deepfilter element alone are set forth in the following table. Given thefilter element occupies 4 square feet, the numbers below divided by 4square feet will provide the air flow per square foot of face areaoccupied by the filter element as s whole alone without prefilter (e.g.363 cfm at 0.2″ WG pressure).

TABLE 2 0.1″ WG  959 CFM 0.15″ WG 1231 CFM 0.20″ WG 1453 CFM 0.25″ WG1658 CFM

Accordingly, for the filter element alone, the corresponding volumetricadvantage (for an almost 6 inch pleat depth having a filter envelopevolume of 1.9 cubic feet) is as follows in the following table:

TABLE 3 0.1″ WG 505 CFM/cu. ft. 0.15″ WG 647 CFM/cu ft. 0.20″ WG 764CFM/cu ft. 0.25″ WG 873 CFM/cu ft.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) is to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

1. A filter assembly, comprising: a rectangular inlet frame having arectangular inlet opening; a rectangular outlet frame; a housing bodybeing collapsible to have a flattened shipping state and an erect state,the collapsible housing body in the erect state being rectangular andinterposed between the rectangular inlet frame and the rectangularoutlet frame in an assembled state; at least one filter having filtermedia installed in the rectangular inlet opening in generally sealingrelation thereto and projecting from the inlet frame toward the outletframe in the assembled state.
 2. The filter assembly of claim 1, whereinthe rectangular inlet frame defines a rectangular recess having aseating surface in surrounding relation of the rectangular inletopening, wherein the at least one filter includes a primary filtercomprising: at least one of a V-bank filter and a rectangular filterthat includes filter media that is at least 3 inches deep, the primaryfilter having an outer peripheral flange seated against the seatingsurface; and a prefilter upstream of the primary filter and seatedagainst an upstream face of the outer peripheral flange.
 3. The filterassembly of claim 2, comprising a first rectangular gasket interposedbetween the outer peripheral flange of the primary filter and theseating surface forming a seal therebetween.
 4. The filter assembly ofclaim 3, further comprising a second rectangular gasket interposedbetween the upstream surface of the outer peripheral flange and theprefilter.
 5. The filter assembly of claim 3, further comprising:compression clips mounted on an outwardly facing side of the rectangularinlet frame, the clips engaging the prefilter to retain the prefilter;and at least two clips compressing the primary filter and the firstrectangular gasket against the seating surface.
 6. The filter assemblyof claim 5, wherein the clips are rotatable relative to the inlet frameto have a compression portion that moves over the rectangular recess forcausing compression, when the clips can be rotated such that the clipsare clear of the rectangular recess to allow removal of the primaryfilter and the prefilter.
 7. The filter assembly of claim 1, furthercomprising first and second housing gaskets having a rectangular shape,the first housing gasket sealing between the rectangular outlet frameand the housing body, the second housing gasket sealing between therectangular inlet frame and the housing body.
 8. The filter assembly ofclaim 7, further comprising a plurality of snap fasteners securing thehousing body to each of the rectangular outlet frame and the rectangularinlet frame to maintain the first and second housing gaskets in a stateof compression.
 9. The filter assembly of claim 8, wherein the snapfasteners comprise buttons attached to the housing body and projectoutwardly therefrom, each of the rectangular outlet and inlet frameshaving a rectangular L-shaped bracket portion with a seating recessreceiving the first and second housing gaskets, respectively, with thehousing body installed inside outer walls of the rectangular outlet andinlet frames, the outer walls having mounting holes through which thebuttons project to fasten in snapped relation.
 10. The filter assemblyof claim 1, wherein the rectangular outlet frame has a solid panelfacing the inlet opening, the solid panel having an opening customizedand matched to a corresponding air flow opening of a building.
 11. Thefilter assembly of claim 1, wherein the rectangular outlet frame and therectangular inlet frame are molded of material comprising plastic; andwherein the housing body comprises corrugated wall board comprisingplastic material, the corrugated wall board having integral hingesformed therein to provide for folding flat and for assembly into aconfiguration for interposition between rectangular inlet and outletframes, the inlet frame further including a grid-work to provide atleast two of said rectangular inlet openings for separate filterelements to be installed into each rectangular inlet opening.
 12. Thefilter assembly of claim 2, wherein the filter assembly is installed inan animal confinement building, the primary filter having a filter mediarated to filter PRRSV from air flow into the building, and wherein theprefilter filters dust to prevent premature plugging of the primaryfilter.
 13. The filter assembly of claim 1, wherein the rectangularinlet frame defines a rectangular recess having a seating surface insurrounding relation of the rectangular inlet opening, wherein the atleast one filter includes a single-header box filter having an outerperipheral flange seated against the seating surface, and furtherincludes a prefilter upstream of the single-header box filter, theprefilter seated against an upstream face of the outer peripheralflange.
 14. A filter assembly, comprising: an inlet frame having aninlet opening; an outlet frame; a housing body extending between theinlet frame and the outlet frame; first and second housing gaskets, thefirst housing gasket sealing between the outlet frame and the housingbody, the second housing gasket sealing between the inlet frame and thehousing body; and at least one filter having filter media, the filterinstalled in the inlet opening in generally sealing relation thereto,the filter projecting from the inlet frame toward the outlet frame inthe assembled state.
 15. The filter assembly of claim 14, wherein theinlet frame and the outlet frame are rectangular, wherein therectangular inlet frame defines a rectangular recess having a seatingsurface in surrounding relation to the inlet opening, wherein the atleast one filter includes a primary filter comprising at least one of aV-bank filter and a rectangular filter that includes filter media thatis at least 3 inches deep, the primary filter having an outer peripheralflange seated against the seating surface, and a prefilter upstream ofthe primary filter and seated against an upstream face of the outerperipheral flange.
 16. The filter assembly of claim 15, comprising afirst rectangular gasket interposed between the outer peripheral flangeof the primary filter and the seating surface forming a sealtherebetween.
 17. The filter assembly of claim 16, further comprising asecond rectangular gasket interposed between the upstream face of theouter peripheral flange and the prefilter.
 18. The filter assembly ofclaim 16, further comprising: compression clips mounted on a anoutwardly facing side of the inlet frame, the clips engaging theprefilter to retain the prefilter; and at least two clips compressingthe primary filter and the first rectangular gasket against the seatingsurface.
 19. The filter assembly of claim 18, wherein the clips arerotatable relative to the inlet frame to have a compression portion thatmoves over the rectangular recess for causing compression, wherein theclips can be rotated such that the clips are clear of the rectangularrecess to allow removal of the primary filter and the prefilter.
 20. Thefilter assembly of claim 14, further comprising a plurality of snapfasteners securing the housing body to each of the outlet frame and theinlet frame to maintain the first and second housing gaskets in a stateof compression.
 21. The filter assembly of claim 20, wherein the snapfasteners comprise buttons attached to the housing body and projectoutwardly therefrom, each of the outlet and inlet frames having anL-shaped bracket portion with a seating recess receiving the first andsecond housing gaskets, respectively, with the housing body installedinside outer walls of outlet and inlet frames, the outer walls havingmounting holes through which the buttons project to fasten in snappedrelation.
 22. The filter assembly of claim 21, wherein the outlet framehas a solid panel facing the inlet opening, the solid panel having anopening customized and matched to a corresponding air flow opening of abuilding.
 23. The filter assembly of claim 22, wherein the outlet frameand the inlet frame are molded of material comprising plastic; andwherein the housing body comprises corrugated wall board comprisingplastic material, the corrugated wall board having integral hingesformed therein to provide for folding flat and for assembly into arectangular configuration, the inlet frame further including a grid-workto provide at least two of said inlet openings for separate filterelements to be installed into each inlet opening.
 24. The filterassembly of claim 15, wherein the filter assembly is installed in ananimal confinement building, the primary filter having a filter mediarated to filter PRRSV from air flow into the building and wherein theprefilter filters dust to prevent premature plugging of the primaryfilter.
 25. A method of assembling an air filter housing, comprising:providing an inlet frame, an outlet frame, and a collapsed housing bodyhaving a generally flattened state; erecting the housing body to atubular shape adapted to mate with the inlet and outlet frames;fastening the housing body to each of the inlet frame and the outletframe; and mounting the air filter housing to a building.
 26. The methodof claim 25, further comprising installing the air filter housing in ananimal confinement building in a location to filter external airentering the animal confinement building; and housing a primary filterhaving a filter media rated to filter PRRSV from air flow into thebuilding, and housing a prefilter upstream of the primary filter,wherein the prefilter filters dust to prevent premature plugging of theprimary filter.
 27. The method of claim 26, further comprising providinga panel across the outlet frame, cutting the panel to match an openingprovided in the animal confinement building, and securing the air filterhousing over the opening in the animal confinement building whilesealing therebetween.
 28. The method of claim 25 further comprising,sealing between the housing body and each of the inlet and outletframes.
 29. A method of installing a filter assembly into an animalconfinement building, comprising: installing a bottom housing panel overan air flow opening in the animal confinement building; cutting thebottom housing panel to have an outlet opening matching the air flowopening; assembling an upper portion of the filter housing to the bottomhousing panel, the upper portion including at least one inlet opening;and installing at least one filter element into the inlet opening. 30.The method of claim 29, further comprising: providing an inlet frame anda housing body to construct the upper portion; erecting the housing bodywith a tubular shape between the inlet frame and the bottom housingpanel; and fastening the housing body to each of the inlet frame and theoutlet frame.
 31. The method of claim 30 further comprising, sealingbetween the housing body and each of the inlet and outlet frames. 32.The method of claim 30, further comprising: arranging the filterassembly in the animal confinement building in a location to filterexternal air entering the animal confinement building; and housing theat least one filter element having a filter media rated to filter PRRSVfrom air flow into the building, and housing a prefilter upstream of theat least one filter element, wherein the prefilter filters dust toprevent premature plugging of the at least one filter element.